The coloring materials for inks used in inkjet recording systems can be broadly classified into materials that use pigments and materials that use dyes, and there is a growing tendency for the use of inks that use pigments as the coloring materials, as such inks exhibit the excellent levels of light resistance, weather resistance and water resistance that are required for high image quality printing.
In terms of the solvent, inks can be broadly classified into aqueous inks and non-aqueous inks. Non-aqueous inks that do not use water as the ink solvent, including solvent-based inks that use a volatile solvent as the main constituent and oil-based inks that use a non-volatile solvent as the main constituent, exhibit good drying properties to aqueous inks, and also display excellent printability.
In non-aqueous inks, a pigment dispersant that dissolves in the solvent is generally used, but because this pigment dispersant improves the affinity between the solvent and the pigment, when the solvent penetrates into the recording paper, the pigment tends to be also drawn into the interior of the recording paper. As a result, the print density tends to fall, and show-through becomes more prevalent.
Accordingly, a non-aqueous pigment ink has been proposed that uses as a dispersant non-aqueous resin dispersion microparticles (NAD=Non Aqua Dispersion) having a pigment dispersion capability.
Prior Art Documents
Patent Documents
Patent Document 1: Japanese Patent Laid-Open No. 2007-197500